This invention relates to a computer or a computer system using a storage, and more particularly, to a computer system for executing copy processing of data in a storage area of a storage.
Computer systems employed in business and other organizations are using more and more volumes as storage areas for storing data. The reasons behind this include increasing data capacity of the storage and prolonged data preservation period.
A computer and storage in a computer system can set only a limited count of volumes, which could hinder the computer system from providing as many volumes as necessary.
A known solution to this problem is to improve the volume utilization efficiency by setting, canceling, and switching the allocation of plural volumes in an actual storage, or plural volumes in a different storage which is connected to the former storage, without changing volume identification information (e.g., WWW: World Wide Name or LUN: Logical Unit Number) that is recognized by the computer (refer to JP 2005-209149 A).
This volume allocation technique includes switching between volumes in the same storage and switching from a volume in the storage to a volume in a different storage which is connected to the former storage.
The volume of the different storage connected to the storage in the latter method is called a real volume. A volume to which a real volume is allocated as its substance and which constitutes the unit of management within the storage will hereinafter be called a virtual volume.